高残炭酚醛树脂的研究进展

综述了高残炭酚醛树脂:硼改性、钼改性、芳基酚改性及硅氮烷改性酚醛树脂,酚三嗪树脂,苯并恶嗪树脂的研究进展。上述改性后的酚醛树脂,耐热性显著提高。这些研究为耐烧蚀材料的应用提供了理论依据,为新一代的高残炭树脂的开发提供了方向。最后指出酚醛树脂在今后的耐烧蚀材料领域仍然会发挥重要的作用。     

Thermosetting resin system based on novolak and bismaleimide for resin‐transfer molding

A thermosetting resin system for resin‐transfer molding based on novolak and bismaleimide (BMI) was developed. The novolak resin was allylated and BMI was used as the curing agent, and allyl phenyl ether, as the diluent. The viscosity–temperature curve and the viscosity–time curve were used to characterize the processing property of the resin system. The resin system had a long pot life at the injection temperature. Based on the DSC data, a regime for the curing and postcuring cycles was established. The cured resin showed outstanding heat resistance and good flexural properties. Composites based on the resin system and woven glass fabric were fabricated using RTM technology. The composites showed very good flexural properties at room temperature and high retention rates at 200 and 300°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1651–1657, 2002     

Curing kinetics and viscosity change of a two‐part epoxy resin during mold filling in resin‐transfer molding process

The curing kinetics and the resulting viscosity change of a two‐part epoxy/amine resin during the mold‐filling process of resin‐transfer molding (RTM) of composites was investigated. The curing kinetics of the epoxy/amine resin was analyzed in both the dynamic and the isothermal modes with differential scanning calorimetry (DSC). The dynamic viscosity of the resin at the same temperature as in the mold‐filling process was measured. The curing kinetics of the resin was described by a modified Kamal kinetic model, accounting for the autocatalytic and the diffusion‐control effect. An empirical model correlated the resin viscosity with temperature and the degree of cure was obtained. Predictions of the rate of reaction and the resulting viscosity change by the modified Kamal model and by the empirical model agreed well with the experimental data, respectively, over the temperature range 50–80°C and up to the degree of cure α = 0.4, which are suitable for the mold‐filling stage in the RTM process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2139–2148, 2000     

Acetyl‐capped paraformaldehyde as crosslinking agent for BMI‐modified novolac resin for resin transfer molding

Paraformaldehyde was end‐capped with acetyl groups and was applied as a crosslinking agent for a bismaleimide (BMI)‐modified novolac resin system. The processibility of the resin system containing 5 wt % crosslinking agent still met the need for resin transfer molding (RTM), whereas the thermomechanical properties of crosslinked resin improved significantly. The composites based on the resin system and woven glass fabric showed better flexural strength, modulus, and higher retention rates at 200 and 300°C than that based on a resin system without acetyl‐capped paraformaldehyde. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1265–1271, 2002     

Preparation of VB‐a/POSS hybrid monomer and its polymerization of polybenzoxazine/POSS hybrid nanocomposites

A benzoxazine monomer (VB‐a) containing an allyl groups was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine (bisphenol‐A and allylamine as VB‐a). This monomer was then reacted with polyhedral oligomeric silsesquioxane (POSS) through hydrosilylation, followed by thermal curing to form poly(VB‐a)/POSS hybrid nanocomposites. The curing behavior of the nanocomposites was monitored using Fourier transform infrared spectroscopy (FTIR), and their thermal and morphological properties were investigated through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy. DMA revealed that the glass transition temperatures of the poly(VB‐a)/POSS nanocomposites were higher than that of the pristine poly(VB‐a), presumably because the POSS cages effectively hindered the motion of the polymer chains. TGA confirmed that the thermal degradation temperatures and char yields of the polybenzoxazines increased after incorporation of the POSS moieties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Experimental characterization of traditional composites manufactured by vacuum‐assisted resin‐transfer molding

The primary purpose of this study is to investigate the anisotropic behavior of different glass‐fabric‐reinforced polyester composites. Two commonly used types of traditional glass fabrics, woven roving fabric and chopped strand mat, have been used. Composite laminates have been manufactured by the vacuum infusion of polyester resin into the fabrics. The effects of geometric variables on the composite structural integrity and strength are illustrated. Hence, tensile and three‐point‐bending flexural tests have been conducted at different off‐axial angles (0, 45, and 90°) with respect to the longitudinal direction. In this study, an important practical problem with fibrous composites, the interlaminar shear strength as measured in short‐beam shear tests, is discussed. The most significant result deduced from this investigation is the strong correlation between the changes in the interlaminar shear strength values and fiber orientation angle in the case of woven fabric laminates. Extensive photographs of fractured tensile specimens resulting from a variety of uniaxial loading conditions are presented. Another aim of this work is to investigate the interaction between the glass fiber and polyester matrix. The experiments, in conjunction with scanning electron photomicrographs of fractured surfaces of composites, are interpreted in an attempt to explain the interaction between the glass fiber and polyester. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of a novel siloxane‐imide‐containing polybenzoxazine

A novel siloxane‐imide‐containing polybenzoxazine based on N,N′‐bis(N‐phenyl‐3,4‐dihydro‐2H‐benzo[1,3]oxazine)‐5, 5′‐bis(1,1′,3,3′‐tetramethyldisiloxane‐1,3‐diyl)‐bis(norborane‐2,3‐dicarboximide) (BZ‐A1) was successfully synthesized. The thermal properties of BZ‐A1 are superior to those of conventional polybenzoxazines lacking siloxane groups. Polymerized BZ‐A1 possesses extremely low surface free energy (γ_s = 15.1 mJ m^?2) after curing at 230 °C for 1 h. Moreover, the surface free energy of polymerized BZ‐A1 is more stable than conventional bisphenol A‐type polybenzoxazine during thermal curing and annealing processes, indicating that polymerized BZ‐A1 is more suitable for applications requiring low surface free energy materials for high temperatures over long periods of time. Copyright © 2010 Society of Chemical Industry     

Bismaleimide resin modified with diallyl bisphenol A and diallyl p‐phenyl diamine for resin transfer molding

O,O′‐diallyl bisphenol A (DBA) and N,N′‐diallyl p‐phenyl diamine (DPD) were used for the reactive diluents of 4,4′‐bismaleimidodiphenol methane (BDM). The objective was to obtain a modified BDM resin system suitable for resin transfer molding (RTM) process to prepare the advanced composites. The processing behavior was determined by time–temperature–viscosity curves, gel characteristics, and differential scanning calorimetry (DSC). The injection temperature of the resin system in RTM could be 80°C, at which its apparent viscosity was only 0.31 Pa/s, and the apparent viscosity was still less than 1.00 Pa/s after the resin was held at 80°C for 16 h. The gel time test result indicated that at low temperatures, the reactivity of the resin system is low, whereas at high temperatures, the resin could cure very fast, which was beneficial to RTM. The postcure of the cured resin at a given temperature was necessary because the resin had a wide and flat cure exothermic peak, observed by DSC curve. The cured resin displayed both high heat and hot/wet resistance and high mechanical properties, especially tensile strength, tensile modulus, and flexural strength at room temperature, which reached 96.2 MPa, 4.8 GPa, and 121.4 MPa, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2245–2250, 2001     

Study of surface‐functionalized nano‐SiO2/polybenzoxazine composites

A series of the surface‐functionalized nano‐SiO₂/polybenzoxazine (PBOZ) composites was produced, and an attempt was made to improve the toughness of PBOZ material, without sacrificing other mechanical and thermal properties. A benzoxazine functional silane coupling agent was synthesized to modify the surface of nano‐SiO₂ particles, which were then mixed with benzoxazine monomers to produce the nano‐SiO₂‐PBOZ nanocomposites. The notched impact strength and the bending strength of the nano‐SiO₂‐PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano‐SiO₂. At the same load of nano‐SiO₂, the nano‐SiO₂‐PBOZ nanocomposites exhibit the highest storage modulus and glass‐transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO₂/PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano‐SiO₂ content and were from 368°C (of the neat PBOZ) to 379°C or 405°C (of the neat PBOZ) to 426°C in air or nitrogen with additional 3 wt % nano‐SiO₂. The weight residue of the same nanocomposite was as high as 50% in nitrogen at 800°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Textural analysis for better correlation of the char yield of pyrolysed lignocellulosic materials

A new empirical formula, based on the surface fractal dimension, the porosity, the botanical composition and the ash content of the precursor is proposed for the assessment of the char yield, Y (wt %) of lignocellulosic materials pyrolysed in a 600-900 °C temperature range. The following equation is proposed:

     

Mechanical and dynamic mechanical analysis of hybrid composites molded by resin transfer molding

This work aims to evaluate the performance of glass/sisal hybrid composites focusing on mechanical (flexural and impact) and dynamic mechanical analyses (DMTA). Hybrid composites with different fiber loadings and different volume ratios between glass and sisal were studied. The effect of the fiber length has also been investigated. The densities of the composites were compared with the theoretical values, showing agreement with the rule of mixtures. The results obtained in the flexural and impact analysis revealed that, in general, the properties were always higher for higher overall reinforcement content. By DMTA, an increase in the storage and loss modulus was found, as well as a shift to higher values for higher glass loading and overall fiber volume. It was also noticed an increase in the efficiency of the filler and the calculated activation energy for the relaxation process in the glass transition region. The fiber length did not significantly change the results observed in all analyses carried out in this work. The calculated adhesion factor increased for higher glass loadings, meaning the equation may not be applied for the system studied and there are other factors, besides adhesion influencing energy dissipation of the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Compounding and injection molding of polybutene‐1/polypropylene blends

The effect of shear‐controlled orientation injection molding (SCORIM) was investigated for polybutene‐1/polypropylene blends. This article reports on the methods and processing conditions used for blending and injection molding. The properties of SCORIM moldings are compared with those of conventional moldings. SCORIM is based on the application of specific macroscopic shears to a solidifying melt. The multiple shear action enhances molecular alignment. The moldings were investigated with mechanical tests, differential scanning calorimetry studies, and polarized light microscopy. The application of SCORIM improved Young's modulus and the ultimate tensile strength. The gain in stiffness was greater for higher polybutene‐1 content blends. A drastic decrease in the strain at break and toughness was observed in SCORIM moldings. The enhanced molecular orientation of SCORIM moldings resulted in a featureless appearance of the morphology. Interfacial features due to segregation were visible in the micrographs of SCORIM moldings. Both conventional and SCORIM moldings exhibited form I′ in polybutene‐1. This article explains the relationship between the mechanical properties and micromorphologies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 806–813, 2003     

真空辅助树脂灌注配套基体树脂的制备及性能

针对真空辅助成型技术(VARI)对基体树脂的特殊要求,结合航空材料对性能的高要求,研制了BA9912中温固化环氧树脂体系。采用VARI工艺制备了G0827/BA9912复合材料,测试了BA9912树脂浇注料及其复合材料的力学性能和耐热性能,并与国内外同类树脂进行了适当的比较分析。分析测试结果表明,BA9912树脂具有良好的力学性能、耐热性能和工艺性能,能够满足VARI成型工艺要求,适合在航空航天领域中应用。     

生物基聚苯并嗪/纤维素纳米晶超疏水防腐蚀涂层的制备及性能

以腰果酚、十八胺和多聚甲醛为原料合成出生物基苯并嗪单体,以单宁酸为固化剂,采用差示扫描量热分析技术和红外光谱考察了苯并嗪单体的热固化行为,结果表明单宁酸可以有效降低苯并嗪的开环固化温度。在钢片表面首先制备聚苯并嗪涂层作为底漆,再通过在涂层中掺杂氨基修饰纤维素纳米晶制备面漆,构建出静态水接触角为161.1°±2.9°的生物基超疏水防腐蚀涂层（PBTC）。该超疏水涂层表现出良好的耐高低温性能和耐刮擦性。电化学测试结果表明PBTC涂层在NaCl水溶液中浸泡30天后仍然具有良好的防腐蚀性能。     

Preparation and performance of high refractive index silicone resin‐type materials for the packaging of light‐emitting diodes

A novel high refractive index and highly transparent silicone resin‐type material for the packaging of high‐power light‐emitting diodes (LEDs) is introduced, which was synthesized by hydrosilylation of vinyl end‐capped methylphenyl silicone resin and methylphenyl hydrosilicone oil catalyzed by Karstedt's catalyst. The vinyl end‐capped methylphenyl silicone resins were prepared by hydrolysis?polycondensation method from methylphenyl diethoxysilane (MePhSi(OEt)₂), phenyl triethoxysilane (PhSi(OEt)₃), and vinyl dimethylethoxy silane (Me₂ViSiOEt) in toluene/water mixture catalyzed by cation‐exchange resin. The vinyl end‐capped methylphenyl silicone resins were characterized by ¹H‐NMR and Fourier‐transform infrared. The performances of the cured silicone resin‐type materials for LED packaging have been examined in detail. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synergistic effect of phosphorus,nitrogen, and silicon on flame‐retardant properties and char yield in polypropylene

In this study, several flame retardants (FRs), containing phosphorus, nitrogen, and silicon, were synthesized. These synthesized FRs were blended with polypropylene (PP) to obtain mixture samples. The flame‐retardant properties of these mixture samples were estimated by the limiting oxygen index (LOI) value and thermal stabilities were characterized by thermogravimetric analysis. The LOI values of these samples were improved from 17.0 to 26.0 and the char yield increased from 0 to 27 wt %. A comparison of these samples, with respect to their LOI values and carbon yield, showed that the FRs, which simultaneously contained phosphorus, nitrogen, and silicon elements, can provide materials with the best flame‐retardant properties, suggesting that there is a synergistic effect among the three elements on the flame‐retardant properties and char yield when they are used in PP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 854–860, 2005     

Physical and mechanical properties of flexible polybenzoxazine resins: Effect of aliphatic diamine chain length

A series of linear aliphatic diamine‐based benzoxazine monomers has been polymerized into transparent, crosslinked specimens that are free of voids and have good mechanical integrity. The density of these polybenzoxazines is measured as a function of the amine chain length. Dynamic mechanical analysis of these linear aliphatic polybenzoxazines shows two, chain length dependent transitions. Properties, such as room temperature modulus, glass transition temperature, crosslink density, thermal degradation temperature, and char yield, of the polybenzoxazines are investigated as a function of the chain length. All these properties exhibit strong dependence on the chain length. These aliphatic amine‐based polybenzoxazines are found to be much more flexible than the bisphenol‐type polybenzoxazines. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2798–2809, 2006     

A diallyl bisphenol A ether and diallyl phenyl ether modified bismaleimide resin system for resin transfer molding

A modified bismaleimide (BMI) resin system for resin transfer molding was prepared by using o,o′‐diallyl bisphenol A ether and 1,4‐diallyl phenyl ether as reactive diluents for BMI. The processing behavior was studied through time–temperature–viscosity curves, gel characteristics, and differential scanning calorimetry. The results indicate that the injection temperature can be 80°C, at which its apparent viscosity is only 0.30 Pa · s. Moreover, after it had been maintained at 80°C for 15 h, the apparent viscosity was still less than 1.00 Pa · s. The cured resin had remarkable heat resistance, hot/wet resistance, and mechanical properties. The heat stability and mechanical properties of the composite based on this resin system and woven glass cloth are also discussed. For short beam shear strength, in tests at 150 and 180°C, 90 and 65% of the original room temperature strength was retained. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1649–1653, 1999     

Fabrication and characteristics of graphene‐reinforced silver nanowire/polybenzoxazine/epoxy copolymer composite thin films

In this study, composite thin films were fabricated by mixing one‐dimensional silver nanowires (AgNWs) with graphene, polybenzoxazine (PBZ) and epoxy. Their electrical and thermal properties under different environmental conditions were investigated. The AgNWs were prepared by a polyol reduction method using ethylene glycol as a reducing agent and polyvinylpyrrolidone as a soft template to reduce silver ions. High aspect ratio AgNWs were then mixed into polymer matrices to allow them to form electrical and thermal conductive paths. Next, a trace amount of graphene was added into the nanocomposites in order to enhance their electrical and thermal properties. The results showed that the addition of graphene and AgNWs improved the threshold leakage current, and a 33% increase in thermal diffusivity was observed. The water resistance and gas barrier properties of PBZ and graphene effectively improved the thermal oxidation stability, and a 200% increase in electrical conductivity was achieved after 120 h of thermal oxidation treatment. A considerable difference was observed between the moduli of epoxy and PBZ. Hardness and phase analyses using atomic force microscopy showed that material modulus mismatch occurred across the interface between the materials, triggering phonon scattering. However, the increase in thermal conductivity was not significant for either material. © 2018 Society of Chemical Industry     

Multi-component nanocomposites of epoxy/silsesquioxane reinforced with carbon fibers and carbon nanotubes processed by resin transfer molding

ABSTRACT

In this work, an epoxy resin modified by silsesquioxane oligomers was used to produce multi-component nanocomposites reinforced with carbon fiber (CF) and multi-walled carbon nanotubes (CNT) by resin transfer molding (RTM). The combination of sonication process with the incorporation of silsesquioxane domains (i.e. increasing the degree of crosslinking of the epoxy matrix), improved the mechanical strength of the hybrid matrix and hybrid/CF/CNT nanocomposites. The multi-component nanocomposites produced by RTM presented Young modulus of 35 ± 8 GPa, tensile strength of 303 ± 41 MPa and impact strength of 1.0 ± 0.3 kJ m^?1. The results showed a significant increase in the tensile strength and impact resistance of the epoxy matrix by the incorporation of silsesquioxanes and sonication before curing of the matrices, showing the promising potential of this multi-component nanocomposite for pipelines and other structural applications.